Thread waxing device



Dec. 4, 195] J MCCARTHY 2,576,961

THREAD WAXING DEVICE Filed April 8, 1949 Patented Dec. 4, 1951 UNITEDSTATES PATENT OFFICE THREAD WAXING DEVICE John F. McCarthy, Lynn, Mass.,assignor to United Shoe Machinery Corporation, Flemington, N. J., acorporation of New Jersey Application April 8, 1949, Serial No. 86,349

2 Claims. 1

The present invention relates to thread waxing devices adapted for usein shoe sewing machines and to improvements in strippers for waxingdevices more particularly with regard to their case in adjustment andeffectiveness during continued use. As hereinafter illustrated, the exemplified Wax stripper is of the type disclosedin United States LettersPatent No. 1,015,772. granted January 30, 1912 upon application of FredAshworth.

The stripper of the patent above referred to is of desirableconstruction and comprises a perforated and compressible rubber plugsupported in a split sleeve formed with one end open and a perforatedwall at the other end. For mounting the sleeve it is enclosed loosely ina socket and cooperating therewith is a perforated compressor retainedin position by a cap having a screw threaded engagement with the socket,the compressor being provided with a flat plug engaging surface actingdirectly at right angles to the length of the thread passing tliroughtheplug. The purpose of the patented construction is to facilitate removaland insertion of the compressible rubber stripper plug supported withinthe sleeve.

When the plug of the patent is first inserted within the split sleeve itis compressed by actuation of the compressor cap until the plug conformsclosely with the thread passing through the perforation therein. Theperforated plug of the patent has both ends cut squarely at right anglesto the length of the thread. For this reason the frictional reaction ofthe thread on the compressible rubber of the plug tends to crowdtogether that end of the perforation in the plug first entered by thethread, compressing the thread sharply as it enters. As a result, thesurplus wax on the thread is substantially all wiped off the outerthread surface by the compression of the plug material against thethread as it enters the plug, subjecting the plug around the perforationat the point of entry of the thread to maximum abrasion by the thread.Continued wear of the inner surfaces of the perforation requiresfrequent tightening of the cap and makes necessary an adjustment of thecompressor cap to apply further pressure on the plug. Eventually theplug becomes so worn around its perforation that replacement isrequired.

The object of the present invention is to produce a thread waxing devicehaving a compressible perforated stripper plug together with supportingmeans for the plug which will increase the durability of the plug,improve the waxing and stripping action on the thread and avoid thenecessity of frequent adjustment of the compressor cap in the holder,while retaining all of the advantages of the waxing device disclosed inthe patent. A further object is to reduce substantially the frequency ofreplacement for a stripper plug in a thread waxing device. The waxingdevice embodying the features of the present invention, accordinglycomprises a stripper plug, a supporting sleeve and a compressor similarto those of the patent except that the end wall of the sleeve and theplug engaging end of the compressor are formed internally with conicalrecesses, the conical angle on the compressor end wall surface beingsubstantially less than that on the end wall of the sleeve, in which acompressible-perforated plug is employed having tapered ends in itsuncompressed condition, the angles of taper of which correspond to theconical angles in the sleeve end wall surface and in the compressor,respectively. By so forming the plug it fits accurately within thesupporting sleeve under all degrees of compression. This is true bothafter the plug has been subject to substantial wear as well as when anew plug is first inserted in the supporting sleeve. The life of theplug as a result is increased many times over that of the plug in thepatent and the stripper is effective in use without forcing thecompressor against a new plug with any substantial degree of pressure,as is required in the patented waxing device. Furthermore, the thread,when it enters into the end of the plug having the greater conical angleand emerges from the end of the plug having the lesser conical angle, iswaxed more effectively with the wax forced more deeply inside the threadand the surplus removed more completely from the surface than with priorstrippers.

These and other features of the invention as hereinafter described andclaimed will readily be understood from the following detailedspecification taken in connection with the 'accompanying drawings, inwhich Fig. 1 is a view in front elevation of a wax pot embodying thewaxing device of the present invention;

Fig. 2 is a sectional view on an enlarged scale of the waxing device andupper portion of the cover for the Wax pot illustrated in Fig. l;

Fig. 3 is a detail perspective view of a stripper plug split supportingsleeve illustrated in Fig.

.Fig. 4 is a detail view in half-section; partly diagrammatic, on astill'further enlarged scale of a portion of a waxing device having astripper plug similar to that employed by the prior art illustrating itsmanner of o eration on the thread; and

Fig. 5 is a similar view of a waxing device cmbodying the features ofthe present invention.

The illustrated thread waxing device is intended for use in connectionwith a wax pot Iii through which a sewing thread I2 is passed in thedirection of the arrows of Fig. l. The thread enters a tube I l mountedin a removable cover IE on the wax pot and after being submerged withina bath of liquid wax the thread is drawn through the waxing deviceincluding a perforated compressible rubber stripper plug 18. Thestripper plug is supported within a split sleeve mounted in turn withinan internal seat in an externally threaded socket 22. The socket 22 isclamped by a set screw 23 within an opening in the top of the wax potcover It. To compress the plug against the thread the upper end of theplug is engaged by a compressor 24 loosely mounted in an internallythreaded cap 26 engaging the threads on the socket 22. The purpose insupporting the plug in the split sleeve is to facilitate removal of theplug after its perforation has been enlarged to a point where it is nolonger possible to force the plug into close conformity with the threadso that it is no longer capable of stripping the excess wax properlyfrom the thread.

In the thread waxing device of the Ashwortn patent above noted the waxstripping plug is cut from an extruded length of rubber rod perforatedto guide the thread with flat ended surfaces at right angles to thelength of the thread guiding perforation passing through it. The ends ofthe sleeve and of the compressor engaging the plug are correspondinglyshaped, the arrangement being such that the action of compressing theplug causes a maximum force to be concentrated against the surfaces ofthe thread at the point of entry of the thread within the perforation ofthe plug; For this reason the surplus wax is stripped from the thread atthe point of entry of the thread within the plug, the greatestabrasional pressure on the thread being applied at this point. Thenatural result of the abrasional pressure of the plug on the thread isto indent slightly the material of the plug about the perforation,causing it to move along with the thread in a manner to increase stillfurther the component of abrasional pressure against the thread.Frequently, a vibratory action of the plug on the thread occurs fromthis cause, centered around the point of entry of the thread andgenerally the inner surface of the perforation at the point of threadentry becomes worn rapidly, particularly after a new plug has beeninserted in the waxing device. As soon as the plug becomes worn morepressure on the plug is required to strip the thread properly of surpluswax. Accordingly, the cap corresponding to 26 of Fig. 2 in theaccompanying drawings is screwed down more tightly.

As illustrated in Fig. 4 a square ended stripper plug 28 is shown, theright-hand half having been omitted to avoid duplication. Although theplug supporting sleeve and compressor shown are those illustrated at 20and 24 as in Fig. 2 having conical plug end engaging surfaces, theaction of the illustrated sleeve and compressor is substantially thesame as the flat ended ones of the patent.

Referring-to the diagrammatic portion of Fig.

4, the force of the compressor 24 is illustrated by a vector 30 and isshown as bein directed along a line running from the outside corner ofthe compressor 24. The vector 30 is met by a similar and substantiallyequal vector 32 drawn through the lower outer corner of the square endedplug 28 and representing the force at the end of the sleeve 20. Theresultant of these two vectors is the force applied to the thread by thematerial of the plug around its perforation and is represented by avector 34. The vector 34 is directed downwardly toward the point ofentry of the thread l2 within the perforation of the plug 28. Since themovement of the thread is in an upward direction the frictional actionon the thread tends to indent and thus increase the compression on thematerial of the plug, indicated by the curved surface 29 at the bottomof the plug and correspondingly the vibrational and wearing action onthe plug is increased. Furthermore, the surplus wax is stripped from thethread at its point of entry and accumulates beneath the bottom surfaceof the plug 28 where it frequently builds up sufficient pressure toraise the wax through the split between the halves of the strippersleeve 20 until the wax fills the recess within which the waxing deviceis located in the wax pot cover 16 and overflows the outer surface ofthe cover. This is particularly noticeable when a square ended stripperplug first is inserted in the waxing device. After continued use moreand more pressure is required to bring the plug into proper strippingconformity with the thread. However, in compressing the plug itsresiliency is substantially reduced so that it wears away in contactwith the thread more rapidly than when first inserted and eventuallyfails to strip the thread properly with any degree of pressure. Forthese reasons it is necessary to replace the stripper plug at frequentintervals.

According to the present invention, the necessity of frequentlyreplacing the stripper plug is avoided and an improved waxing action ofthe device on the thread results. To this end the stripper plug I8 isconstructed to impart pressure to the thread in a particularlyadvantageous manner which requires far less compression to the plug thanwith prior plugs, especially when first inserted in the supportingsleeve. Instead of centering the application of pressure on the threadat the point of entry into the plug, the pressure of the plug I8 iscentered nearer the end of the plug from which the thread emerges (seeFig. 5), the thread drawing surplus wax into the perforation in the plugto build up a hydraulic counter-pressure within the perforation. In thisway the wax is forced between the superficial fibers of the thread.giving a deeper ime pregnation and avoiding abrasion of the innersurface of the plug perforation. Furthermore the pressure on the threadis distributed over a considerable area along the length of the thread,producing more of a wiping action than a scrap- 7 ing action as occursin the stripper plug of the prior art. Also, the resultant of theendwise compression forces within the substance of the plug is directedupwardly toward the thread so that the tendency of vibration between thethread and the stripper plug is much less than when the resultant of thecompressional forces in the plug is downwardly as in the prior art.

The wax stripper plug 58, illustrated in Figs. 2 and 5, has tapered ends36 and 38 and a central axial perforation 40 through which the thread I2is drawn from the wax pot I 0. The split sleeve 20 is formed with oneend open but with an internal conical perforated wall at its lowerthread entering end of approximately a 60 angle to the thread instead ofhaving a square end as in the patent. The plug engaging surface of thecompressor 24 at the thread emerging end of the plug is made internallyin conical form disposed at approximately 45 to the thread and thecompressor has a centra1 perforation through which the thread may bedrawn from the plug. The plug has the angles of its tapered ends whilein its uncompressed condition correspondingly shaped and proportioned tofit the conical angles of the sleeve end wall and of the compressorrespectively, the angle of the compressor conical surface beingsubstantially less by at least than that of the sleeve end Wall surface.

Referring to the diagrammatic part of Fig. 5, the direction andintensity of the force applied by the compressor 24 to the plug I8 whenthe thread enters at the lower end of larger conical angle isapproximately represented by the vector 42. The corresponding reactionforce of the end wall conical surface 36 of the sleeve is represented bythe vector 44 and the resultant force is represented by the vector 46.It will be apparent from a consideration of the location and directionof the resultant vector 46 that the pressure on the thread running fromthe end of greater conical angle to the end of lesser conical angle willbe concentrated just above the mid-section of the stripper plug.However, the surplus wax on the thread will not be removed entirely fromthe surface of the thread until the thread reaches the upper end oflesser conical angle on the stripper plug because wax will be drawn intothe perforation at the end of greater conical angle, providing ahydraulic pressure which resists the inward pressure of the plug againstthe thread. For this reason the surplus wax will be drawn to a pointsubstantially above the mid-section of the plu before actual contactoccurs of the plug with the thread. Furthermore, the lower end of theplug fits exactly with the end wall of the sleeve and prevents anyaccumulation of liquid wax between the plug and the sleeve. Thus, thereis no possibility of building up a hydraulic pressure in the wax beneaththe plug such that the wax will be forced upwardly through the splitbetween the halves of the sleeve 20. The wax also is forced into theinner fibers of the thread by the hydraulic wax pressure built up withinthe perforation. Since the pressure of the plug against the thread isdistributed over a greater area than is the pressure in the plug of theprior construction and is resisted by the hydraulic pressure of the waxon the thread, much less pressure is required, less wear occurs fromabrasion of the thread on the plug and the plug itself has a longer lifein actual use.

To enhance the building up of hydraulic pressure in the plug and toexclude the pressure from the space between the lower end of the plugand the end wall of the sleeve 20 the ends of the plug are provided withinternal depressions 48. The upper end is also similarly shaped toinsure concentration of pressure on the thread more definitely at theupper end of the plug. With spective parts.

such construction of the plug not only is a more efiective thread waxingoperation obtained but the useful life of the plug is extended six toeight times. Accordingly, it; is economical to mold each plug properlyin a separate operation rather than to employ cut lengths of an extrudedrod material with square cut ends. Also, it is advantageous to employseparately molded plugs because they are by reason of their moldingoperation of amorphous internal structure which provides a betterwearing characteristic on the thread than is obtained by the extrudedrod material. The extrusion operation tends to elongate the molecularstructure of the rubber into a fibrous form, the fibers of which runlengthwise. Lengthwise fibrous structure does not provide such durablewearing surface engaging the thread inside the plug perforation as anamorphous structure, particularly where the abrasive action is in thesame direction.

The nature and scope of the invention having been indicated and aparticular embodiment having been described, what is claimed is:

l. A thread waxing device having a stripper sleeve formed with one endopen and an internal conical perforated wall at the other end into whichthe thread enters, and a compressor disposed within the open end of thesleeve and formed at the inner end from which the thread emerges with aconical recess of an angle substantially less than the conical angle atthe end wall of the sleeve, in combination with a compressibleperforated wax stripper plug having in its uncompressed conditiontapered ends of substantially diiferent angles of taper corresponding tothe conical angles of the sleeve end wall and of the compressor,respectively, and disposed to fit the corresponding ends of the sleeveand compressor.

2. A thread waxing device having a split stripper sleeve formed with oneend open and an internal conical perforated wall at the other end intowhich the thread enters, the conical angle of said end wall beingapproximately 60, an enclosing socket to receive the sleeve, and acompressor disposed within the open end of the sleeve and formed at itsinner end from which the thread emerges with an internal conical surfacehaving an angle of approximately 45, in combination with a compressibleperforated rubber wax stripper plug having in its uncompressed conditiontapered ends of the same angles of taper as those on the sleeve andcompressor disposed to fit the corresponding ends of the re- JOHN F.MCCARTHY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 528,301 Montgomery Oct. 30, 18941,015,772 Ashworth Jan. 30, 1912 1,882,450 Tyner Oct. 11, 1932 1,943,818Fantone et al. Jan. 16, 1934 2,020,783 Jones Nov. 12, 1935 2,036,048Hinsky Mar. 31, 1936 2,357,168 Bruining Aug. 29, 1944

